The design of a sensitive photodetective element involves consideration of photon absorption, exciton or electron hole pair (EHP) generation and EHP separation. For example, the materials in a silicon p-n junction or a Schottky metal junction are generally good absorbers of visible light radiation. That is, devices incorporating p-n junctions or Schottky metal junctions provide high rates of photon absorption. With the absorption of each photon, there is a probability that the absorbed photon will generate an EHP. If the EHP is generated in the depletion region of the junction, the applied or built in electric field will cause the EHP constituents to drift in opposite directions due to the opposing electric charge signs. If the EHP is not separated by an electric field, the probability is increased that the electron and hole will recombine and reduce the photodetective efficiency of the device.